#include<stdio.h>
#include<errno.h>

int main()
{
    FILE* fd1 = fopen("log1.txt", "w");
    if(fd1 == NULL) return errno;
    printf("fd1->%d\n", fd1->_fileno);

    FILE* fd2 = fopen("log2.txt", "w");
    if(fd2 == NULL) return errno;
    printf("fd2->%d\n", fd2->_fileno);

    FILE* fd3 = fopen("log3.txt", "w");
    if(fd3 == NULL) return errno;
    printf("fd3->%d\n", fd3->_fileno);
    
    printf("stdin ->%d\n", stdin ->_fileno);
    printf("stdout->%d\n", stdout->_fileno);
    printf("stderr->%d\n", stderr->_fileno);
    return 0;
}
